"Belly dump" trucks, i.e., trucks which empty their load through the bottom or "belly" of the truck, have become popular for hauling various products because of certain advantages that they have over conventional end dump trucks. The contents of a belly dump truck are often more conveniently and efficiently loaded and unloaded and transported. Instead of tipping back the loaded portion of the truck to dump out from its end, the belly dump truck simply opens doors located underneath the bed, i.e., in the "belly" of the truck, allowing its contents to exit through the force of gravity.
In contrast to end dump trucks, belly dump trucks usually dump their contents while moving, leaving a continuous pile or trail of material. End dump trucks dump while stationary, and when the pile reaches such a height that the material will no longer leave the truck, the bed is lowered and the truck is moved to an adjacent location to dump another installment of its contents. This process is repeated until the truck is fully emptied, resulting in a series of large piles of material.
Though belly dump trucks often have clear advantages of efficiency, cost, and time effectiveness, they have a distinct disadvantage when large piles of material are more desirable than trails. For example, in the road construction industry belly dump trucks are frequently used to transport "chip" and related material, chip being the gravel or crushed rock which is placed on the road to strengthen and reinforce the asphalt placed thereon. The road laying machinery requires the chip to be in piles such as result from the discharge of end dump trucks. When belly dump trucks are used to haul the chip, their mode of discharge requires further handling of the chip to get it from a trail into piles. When the chip contacts the ground in a trail, however, it is contaminated with dirt, foreign rock material, and other substances which get mixed in the pile of chip and compromise its purity. This not only lessens the quality of the road, it increases the likelihood that the chip will be rejected upon inspection by the client (usually a state road commission), requiring the contractor to bring in a new load. In gathering the chip into piles, therefore, large amounts of chip must be left on the ground to avoid contamination, increasing expense.
There is needed, therefore, an apparatus for unloading a bottom loader which loads the material into piles ready for subsequent use by other machinery, combining the advantages of an end dump truck and a belly dump truck.
On occasion it is also desirable to empty a truck directly into a railcar or other container, which belly dump trucks are presently unable to do.
Warner, U.S. Pat. No. 3,378,152, describes a truck loader onto which trucks drive and unload their contents, whether they be end or belly dump trucks. It provides for a ramp moved by track machinery onto which the trucks drive, and a hopper in the ramp into which the trucks dump their contents, after which the material is transferred to a conveyor which carries it directly to the road laying machinery. The apparatus is not easily transported from job to job, since the track transport system is necessarily slow. This would require that the apparatus be moved by crane or other means into a tractor-trailer or similar transport device to move the apparatus to a different job site. Even if the apparatus were driven under its own power, its width would constitute a problem on highways.
Other devices of interest in the art include Silver, U.S. Pat. No. 3,606,050, and White, U.S. Pat. No. 671,122.